Generally, a detergent for use in removing grime on a bath tub wall is required to meet requirements different from that for the conventional detergents for tablewares, fabrics, etc. One reason for this is that the grime on a bathtub, that is, so-called scum or a bathtub ring, does not necessarily comprise only organic materials.
It is usually considered that the development of the scum in a bathtub may be attributable to stains from the skin and the fat of a human body, formation of an insoluble-lime soap through the use of a soap, inorganic and organic stains, and the like. Among them, the lime soap and the skin and fat grime of the human body are considerably sticky, and when they adhere to surfaces of a bathtub or a bath water heater of water recirculation type, it is difficult to remove.
In order to remove this grime completely with the use of conventional detergents, the work of rubbing heavily the surfaces of the bathtub with a scrubbing-brush, a sponge and the like is required and particularly the work of rubbing the bottom surface of a bathtub requires considerable labor and time.
Furthermore, with a bath water heater of water recirculation type installed outside the bathtub it is impossible to clean throughout the inner surface thereof due to its construction, and only clean cleaning grime out by means of hydraulic pressure provided through ports in communication with the outside is possible, so that no satisfactory effect of cleaning is obtained and the scum gradually accumulates to float out into the bathtub during bathing whereby those having a bath will feel uncomfortable. Such accumulation and floatation of scum must be avoided also from the standpoint of sanitation.
In addition to these problems, when these detergents are used for cleaning a bathtub, they are further unsatisfactory in sudsing, permeability, deodorizing ability, etc.
In cleaning a bathtub, the efficiency of cleaning work depends greatly upon sudsing and the time until the suds disappear which in turn govern the ease and time for rinsing and draining. In order to remove the scum adhering to a bathtub, a detergent should have a strong permeability and solubilization and at the same time should perform the function of removing bad odor resulting from the grime such as scum. That is, a detergent suitable for use for bathtub cleaning is one that has a good sudsing property, a short desudsing time, and strong deodorization and permeability.
Most of the detergents which have heretofore been used for bathtub cleaning comprise abrasives, and the cleaning of the tub has been conducted by a physical operation of rubbing the surface of the tub. As a result, the surface of the tub is liable to be scratched and the cleaning work is troublesome.
Detergents for cleaning toilet ceramic products such as a water closet may be also used for washing the tub, but these detergents are strongly acidic and the rubbing operation using a sponge directly containing these detergents has the great possibility of roughening the user's hands and has a tendency to deteriorate the materials of which the bathtub and bath water heater are made.